אבן העזר ל״בEven HaEzer 32

Se’if 1א׳

בִּשְׁטָר כֵּיצַד, כּוֹתֵב לָהּ עַל הַנְּיָר אוֹ עַל הַחֶרֶס, אַף עַל פִּי שֶׁאֵין בּוֹ שְׁוֵה פְּרוּטָה, "הֲרֵי אַתְּ מְקֻדֶּשֶׁת לִי", וְנוֹתְנוֹ לָהּ בִּפְנֵי עֵדִים. וְצָרִיךְ שֶׁיִּכְתֹּב אוֹתוֹ לְשֵׁם הָאִשָּׁה הַמִּתְקַדֶּשֶׁת, כְּמוֹ בְּגֵט. וְאִם כְּתָבוֹ שֶׁלֹּא לִשְׁמָהּ, אֵינָהּ מְקֻדֶּשֶׁת. וְאֵינוֹ כּוֹתְבוֹ אֶלָּא לְדַעְתָּהּ; וְאִם כְּתָבוֹ שֶׁלֹּא לְדַעְתָּהּ, הֲרֵי זוֹ סָפֵק מְקֻדֶּשֶׁת:

With a document how [is she engaged]? He writes to her on a paper or on a pottery shard even though it is not worth a Perutah "Behold you are engaged to me" and he gives it to her in front of witnesses. And he must write it for the woman he is getting engaged to like with a Get. If he didn't write it for her name, she is not engaged to him. He can only write it by her will, but if he wrote it against her will, she is questionably engaged.

Se’if 2ב׳

אַף עַל פִּי שֶׁהַשְּׁטָר פָּסוּל לְקַדֵּשׁ בּוֹ, שָׁמִין אֶת הַנְּיָר; אִם יֵשׁ בּוֹ שְׁוֵה פְּרוּטָה, מְקֻדֶּשֶׁת, וְאִם לָאו, הֲרֵי זוֹ סָפֵק מְקֻדֶּשֶׁת:

Even if the document is invalid to use for engagement they evaluate the paper, if it was worth a perutah she is engaged but if not she is questionably engaged.

Se’if 3ג׳

אִם הִיא קְטַנָּה אוֹ נַעֲרָה וּמְקַדְּשָׁהּ עַל יְדֵי אָבִיהָ בִּשְׁטָר, כּוֹתֵב: "בִּתְּךָ מְקֻדֶּשֶׁת לִי":

If she were a minor or a young girl [between 12 and 12.5 years old] and she is getting engaged through her father with a document her writes "your daughter is betrothed to me".